The Case of the Secret Tunnel Maisie Hitchins

Enhanced descriptions from Syndetics:

Maisie Hitchins longs to be a detective. She's sure there are lots of adventures to be had on the streets of Victorian London. And, together with her faithful puppy, Eddie, she is determined to follow even the slightest scent of a mystery - no matter what!
In Book 5 of the Maisie Hitchins series, Maisie is intrigued by a new lodger, Mr Fred Grange, who isn't quite what he seems... Mr Grange claims to work as a clerk for a biscuit company, but he's out and about on the London streets at odd hours, and Maisie soon discovers something very precious hidden in his rooms. Determined to unmask him as a thief, she soon discovers that the truth is far more complicated - and dangerous. Before long, Maisie and her friends are led into a web of mystery lurking underground...
A fantastic mystery series from best-selling author Holly Webb, packed with adventure, Maisie Hitchins is perfect for readers aged six to eight years.

Reviews provided by Syndetics

Horn Book Review

In the fifth book, Maisie's grandmother's boarding house has a new lodger, Mr. Grange. Twelve-year-old Maisie thinks he's very dull--until she notices suspicious things about him. Is he part of an art-smuggling ring in London's underground tunnels? The simple mystery plot and well-placed clues are appropriate for a young middle-grade audience; black-and-white line drawings help establish the Victorian setting. (c) Copyright 2017. The Horn Book, Inc., a wholly owned subsidiary of Media Source, Inc. No redistribution permitted.